I have no reason to doubt the findings of a new study by Massachusetts Institute of Technology researchers that examines how COVID-19 is transmitted in indoor spaces. In fact, the findings comport with what I surmised or at least intuitively believed from an early stage of the pandemic.

The first outbreaks I examined involved cruise ships, one particular woman who served as a super-spreader in South Korea, and the outbreak in Washington state, which included a choir practice. From all of those examples, I concluded that transmission was primarily airborne and based on the concentration or build up of viral particulates in the air. That didn’t mean we couldn’t get infected in the more traditional way, by touching a water faucet or door knob, but it meant that the early focus on disinfecting surfaces was at least insufficient to provide protection.

Health authorities were very late in coming to this conclusion, in part I believe because they understood how economically disruptive it would be if they told people it is unsafe to gather indoors. But I, as a non-scientist, was convinced of the danger from nearly the beginning and acted accordingly.

I studied whatever I could find on how air moves when people breath, and I concluded that outdoor activities were almost certainly safe, which is why I allowed my son to play baseball and soccer throughout 2020 and beginning again in February of 2021. I did not allow him to attend indoor practices, although I’ve recently relented on a weekly baseball practice with a lone instructor which is conducted in a very large high-ceilinged gym.

The MIT findings give me some pause on that decision, as it’s clear that 60 feet of distance isn’t any safer than six feet in indoor spaces. But, ultimately, it’s very hard for me to picture how viral particulates could become concentrated in that gym. It also helps that everyone in the family except my son is now vaccinated.

The authors of the study make an important point when they suggest that we can use carbon dioxide levels as a proxy for determining the risk level of indoor spaces. This tells us how much exhaled air is circulating, and it’s not hard to envision how some rooms might quickly become dangerous while others almost certainly won’t, particularly if fresh air is constantly introduced. Just picture astronauts trapped in a small capsule without fresh oxygen. The carbon dioxide buildup from their exhalations will eventually overwhelm them, and it won’t matter if they keep six feet of distance from each other.

I do worry that the study’s findings will be misused. The tenor of the CNBC article cited above is that we’re overreacting and keeping too many businesses shuttered or restricted. But the results actually show that in one important way, indoor spaces areĀ moreĀ dangerous than previously believed. Social distancing is not very helpful if you’re in a room with a high concentration of COVID-19 circulating, especially if you spend a lot of time in that space. So, you might keep your distance from everyone else while you’re in the store, but if the store has low ceilings and poor circulation, it’s still quite risky to linger. You definitely would not want to work there.

The findings also confirm that outdoors spaces are extremely safe, although infection is still possible if two people are close enough for long enough. Variants are also a concern, as some are substantially more transmissible. I assume this simply means that infection can occur at lower concentrations, so what might have been safe last year might not be safe this year or in the near future.

The vaccines seem to reduce the likelihood of infection and also to vastly reduce the lethality of infection, so they are the best protection available. Still, they’re not foolproof, so the best idea is to choose your indoor activities carefully and to get in and get out whenever you can. Sitting through a two-hour movie is probably an unnecessary risk, but briskly walking through the grocery store is probably fine, especially if you’ve been vaccinated.

Vaccines are also important for limiting how many variants emerge and for hopefully getting the COVID-19 genie back in the bottle at some point through herd immunity. So, please get vaccinated. And, be smart. You don’t need to stress about every single thing, but having good information about how the disease spreads can help you make good decisions.